The control and modeling of doping profiles and transients in MOVPE growth

Abstract

The accurate placement of dopants during chemical vapor deposition is complicated by many factors: growth temperature, reactor design, flow conditions, and the choice of growth and doping chemistry. Long doping transients have often been noted in structures grown using, for example, dopant precursors such as H2Se and Mg(C5H5)2. These transients appear at the "turn-on" of a dopant source as well as the termination or "turn-off" of the source. The grown-in dopant profiles are also modified by the diffusion of the dopant during the thermal history of the structure. The major cause of these transients in the case of metal-organic doping sources, such as Mg(C5H5)2, is the adsorption and desorption of the dopant precursors on the internal surfaces of the reactor. We have developed a heuristic model of this process which can describe the major features of this process. Growth conditions and dopant source characteristics are described which minimize these growth transients. © 1988.